Nondestructive evaluation of thickness variations for elastic plates by high-overtone bulk acoustic resonance

Abstract

Based on the resonant frequency spectra of a high-overtone bulk acoustic resonance, a model for nondestructive evaluation of the elastic plate thickness is given. The simulations demonstrate that the thickness deviations of the elastic plates are sensitive to two parameters: the parallel resonance frequencies and the spacing of parallel resonance frequencies (SPRF). At the normal and transition regions of the SPRF curves, the parallel resonance frequencies periodically linearly decrease with the increase of thickness deviations, which is applicable for evaluating the thickness deviations of the plates.

Acoustic Energy Regulation and Quality Factor Improvement in Acoustic Liquid Sensors by Optimized Structural Design

“…Although the thicker substrate can have a higher Q, it inevitably induces a high-density frequency spectrum and causes difficulties in the frequency selection. 7) It is obvious that the regulation of acoustic energy and Q's robustness corresponding to the microfluid channel are crucial issues in designing acoustic liquid sensors. In this letter, we will report an acoustic sensor showing a high Q and a fascinating robustness.…”

“…Q of the acoustic sensor at the resonant mode is defined by Q ¼ ð f s =2Þ Â jðdÈ=df Þjj f ¼f s , where È is the phase of the input electric impedance and f s is the series resonant frequency, which corresponds to the maximum conductance. 7) Firstly, we investigate the acoustic energy regulation in the optimized HBAR structure. As we know, Q could approach a high value, which is mainly determined by the substrate as the substrate thickness is much larger than the wavelength.…”